In typical commercial electrostatographic reproduction apparatus (copier/duplicators, printers, or the like), a latent image charge pattern is formed on a uniformly charged charge-retentive or photo-conductive member having dielectric characteristics (hereinafter referred to as the dielectric support member). Pigmented marking particles are attracted to the latent image charge pattern to develop such image on the dielectric support member. The developed image is transferred to a receiver member, such as a sheet of paper, transparency or other medium, in an electric field. After transfer, the receiver member bearing the transferred image is transported away from the dielectric support member, and the image is fixed (fused) to the receiver member by heat and pressure to form a permanent reproduction thereon.
Certain reproduction apparatus have been designed to produce multi-color copies. In such reproduction apparatus, multiple color separation images are respectively developed with complementary colored marking particles, and then transferred in superposition to a receiver member. It has been found that fixing of multi-color marking particle images to a receiver member requires substantially different operating parameters than fixing standard black marking particle images to a receiver member. Moreover, the respective operating parameters may in fact be in contradistinction. That is, multi-color images require a high degree of glossiness for a full, rich depth of color reproduction; on the other hand, since glossiness for black marking particle images may significantly impair legibility, a matte finish is preferred.
Additionally, in the multi-color copy market, many different types of receiver members are utilized. The receiver members vary in surface finish gloss, weight, and thickness. Since the market demands a high quality appearance for finished copies, the image gloss should match the gloss of the selected receiver member, and the gloss of the images on both sides of duplex copies should also match.
It is known that the glossiness of a marking particle image is, at least in part, dependent upon the marking particle melting characteristics in the fusing process and the characteristics of the receiver members. In general, the fusing apparatus serves to soften or at least partially melt the marking particles, enabling the marking particles to permeate into the fibers of the receiver member so that the marking particles are fixed to the receiver member. For example, the fusing apparatus may include a heated roller which contacts the marking particles and the receiver member under pressure. If color marking particle images are not sufficiently melted, light scattering cavities may occur in the copy which degrades the color reproduction. Moreover, if the marking particles on the receiver member do not have a mirror-like surface, incident light is reflected by diffusion from the marking particle surface and is not admitted into the marking particle layers, making the colors on the receiver member appear dark and cloudy.
For efficient overall operation of reproduction apparatus, such apparatus must be capable of satisfactorily accomplishing different copy jobs on receiver members of varying characteristics. The length of the job run, as well as the receiver member characteristics, has been shown to impact fusing and image gloss. Quality fusing and proper gloss, as discussed above, are necessary to provide desirable copy output. At the present time, the typically available reproduction apparatus require some compromises in copy quality. They do not exhibit the wide range of operation necessary to provide for the desired tuning of image gloss so as to match image gloss to the gloss of the selected receiver member, and match the gloss of the images on both sides of duplex copies.